Wave dielectric transmission device, manufacturing method thereof, and in-millimeter wave dielectric transmission method

ABSTRACT

Provided is an in-millimeter wave dielectric transmission device including a first signal processing board for processing a millimeter wave signal, a second signal processing board signal-coupled to the first signal processing board to receive the millimeter wave signal and perform signal processing with respect to the millimeter wave signal, and a viscoelastic member provided between the first signal processing board and the second signal processing board and having a predetermined relative dielectric constant and a predetermined dielectric dissipation factor. The viscoelastic member constitutes a dielectric transmission path. With such a configuration, the viscoelastic member absorbs vibration when external force is applied to the signal processing boards, so that vibration of the first signal processing board and the second signal processing board can be reduced, and a millimeter wave signal between the signal processing boards can be transmitted through the viscoelastic member at a high speed without using connectors and cables.

TECHNICAL FIELD

The present invention relates to an in-millimeter wave dielectrictransmission device which can be applied to an anti-collision radarsystem of a vehicle for transmitting a millimeter wave signal by using adielectric substance as a transmission path, a manufacturing methodthereof, and an in-millimeter wave dielectric transmission method.

In detail, a viscoelastic member having a predetermined relativedielectric constant and a predetermined dielectric dissipation factor isprovided between signal processing boards for transmitting/receiving amillimeter wave signal to absorb vibration of an in-millimeter wavedielectric transmission device formed of the signal processing boards,and high speed data transmission using a millimeter wave signal can beperformed between the signal processing boards through the viscoelasticmember.

BACKGROUND ART

In recent years, with the development of the vehicle industry, thenumber of produced vehicles is increased every year, and about seventymillion vehicles were produced throughout the world in 2007. In-vehicledevices such as car navigation systems and car audio systems are mountedin vehicles around the world. The in-vehicle devices are required topass a temperature test and a humidity test, which are meteorologicaland environmental tests, and a vibration test and a collision test,which are mechanical and environmental tests, and to operate normally inevery region on the earth. In the environmental tests, specifically, thevibration test (the mechanical and environmental test) is performed asan essential environmental test because in-vehicle devices are oftenused in environments with vibration.

For in-vehicle devices, it is significantly important to ensure ananti-vibration property. Among such in-vehicle devices, for example, anelectronic device such as an anti-collision radar system of a vehiclefor performing high speed data transmission using a millimeter wavesignal has seen an increase. An anti-collision radar system is anadoptive speed control device which controls an inter-vehicle distancewith a frontward vehicle as a forward-looking radar according to thespeed using an electromagnetic wave of a millimeter wave band so as toprevents a collision with the frontward vehicle.

An anti-collision radar system has a plurality of signal processingboards therein and processes signals by performing high speed datatransmission of a millimeter wave signal between the signal processingboards. In devices for performing high speed data transmission using amillimeter wave signal used in the in-vehicle devices and the like, itis probable that connectors, cables and the like connected to the signalprocessing boards will be released by vibration from an outside oroperating vibration of the devices themselves.

Specifically, since the connectors and cables for high speed datatransmission have the large number of pins and a complicated structure,the connectors and cables may be easily released from the signalprocessing boards. Patent Literature 1 discloses a connector with arobust structure.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication

SUMMARY OF INVENTION Technical Problem

In Patent Literature 1, adhesive hardening type high-dielectric resin isfilled in a connector and hardened, thereby allowing the structure ofthe connector to be robust. However, since connectors and cables forhigh speed data transmission have the large number of pins, the size ofan electronic device is increased, resulting in an increase in the cost.

The present invention is made in view of the above-mentioned issue, andaims to provide an in-millimeter wave dielectric transmission devicecapable of reducing vibration applied from an outside or vibrationcaused by the operation of an electronic device itself and performinghigh speed data transmission without using connectors and cables forhigh speed data transmission, a manufacturing method thereof, and anin-millimeter wave dielectric transmission method.

Solution to Problem

The above problems are solved by an in-millimeter wave dielectrictransmission device including: a first signal processing board forprocessing a millimeter wave signal; a second signal processing boardsignal-coupled to the first signal processing board to receive themillimeter wave signal and perform signal processing with respect to themillimeter wave signal; and a viscoelastic member provided between thefirst signal processing board and the second signal processing board andhaving a predetermined relative dielectric constant and a predetermineddielectric dissipation factor, wherein the viscoelastic memberconstitutes a dielectric transmission path.

In accordance with the in-millimeter wave dielectric transmission deviceaccording to the present invention, a viscoelastic member having apredetermined relative dielectric constant and a predetermineddielectric dissipation factor is provided between a first signalprocessing board and a second signal processing board, thereby absorbingvibration when external force is applied to the signal processingboards.

A method for manufacturing an in-millimeter wave dielectric transmissiondevice according to the present invention includes the steps of: forminga first signal processing board for processing a millimeter wave signal;forming a second signal processing board for receiving the millimeterwave signal from the first signal processing board and performing signalprocessing with respect to the millimeter wave signal; and providing aviscoelastic member having a predetermined relative dielectric constantand a predetermined dielectric dissipation factor between the firstsignal processing board and the second signal processing board, andforming a dielectric transmission path by the viscoelastic member.

In accordance with the method for manufacturing the in-millimeter wavedielectric transmission device according to the present invention, aviscoelastic member having a predetermined relative dielectric constantand a predetermined dielectric dissipation factor is interposed betweensignal processing boards, thereby manufacturing an in-millimeter wavedielectric transmission device capable of transmitting anelectromagnetic wave.

An in-millimeter wave dielectric transmission method according to thepresent invention allows an in-millimeter wave dielectric transmissiondevice to perform the steps of: generating a millimeter wave signal byperforming signal processing with respect to an input signal; convertingthe generated millimeter wave signal into an electromagnetic wave;transmitting the converted electromagnetic wave to one portion of aviscoelastic member constituting a dielectric transmission path andhaving a predetermined relative dielectric constant and a predetermineddielectric dissipation factor; receiving the electromagnetic wavetransmitted to the other portion of the viscoelastic member constitutingthe dielectric transmission path; converting the receivedelectromagnetic wave into a millimeter wave signal; and generating anoutput signal by performing signal processing with respect to theconverted millimeter wave signal.

In accordance with the in-millimeter wave dielectric transmission methodaccording to the present invention, a viscoelastic member having apredetermined relative dielectric constant and a predetermineddielectric dissipation factor is interposed between a first signalprocessing board and a second signal processing board without usingconnectors or cables, and a millimeter wave signal can be transmitted ina vibration environment at a high speed.

Advantageous Effects of Invention

According to an in-millimeter wave dielectric transmission device, amanufacturing method thereof, and an in-millimeter wave dielectrictransmission method of the present invention, a viscoelastic memberhaving a predetermined relative dielectric constant and a predetermineddielectric dissipation factor is interposed between a first signalprocessing board and a second signal processing board. With such aconfiguration, the viscoelastic member absorbs vibration when externalforce is applied to the signal processing boards, so that vibration ofthe first signal processing board and the second signal processing boardcan be reduced.

Furthermore, the viscoelastic member is interposed between the firstsignal processing board and the second signal processing board withoutusing connectors or cables, and a millimeter wave signal can betransmitted in a vibration environment at a high speed. Consequently, itis possible to provide an in-millimeter wave dielectric transmissiondevice capable of performing high speed signal transmission with highreliability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100 according tothe present invention.

FIG. 2 is a sectional view showing an example of the configuration of anin-millimeter wave dielectric transmission device 100.

FIG. 3 is a block diagram showing an example of the configuration of anin-millimeter wave dielectric transmission device 100.

FIG. 4 is an exploded perspective view showing an assembly example 1 ofan in-millimeter wave dielectric transmission device 100.

FIG. 5 is an exploded perspective view showing an assembly example 2 ofan in-millimeter wave dielectric transmission device 100.

FIG. 6 is a graph showing an example of characteristics of anin-millimeter wave dielectric transmission device 100 according to asimulation.

FIG. 7 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100A according to afirst embodiment.

FIG. 8 is a sectional view showing an example of the configuration of anin-millimeter wave dielectric transmission device 100A.

FIG. 9 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100B according to asecond embodiment.

FIG. 10 is a sectional view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100B.

FIG. 11 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100C according to athird embodiment.

FIG. 12 is a sectional view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100C.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an in-millimeter wave dielectric transmission device, amanufacturing method thereof, and an in-millimeter wave dielectrictransmission method as an embodiment according to the present inventionwill be described with reference to the appended drawings. FIG. 1 is aperspective view showing an example of the configuration of anin-millimeter wave dielectric transmission device 100 according to thepresent invention and FIG. 2 is a sectional view of the in-millimeterwave dielectric transmission device 100 shown in FIG. 1. Thein-millimeter wave dielectric transmission device 100 shown in FIGS. 1and 2 can be applied to an anti-collision radar system and the like of avehicle.

The in-millimeter wave dielectric transmission device 100 includes afirst signal processing board (hereinafter, referred to as a signalprocessing board 101), a second signal processing board (hereinafter,referred to as a signal processing board 201), and a viscoelastic member107.

In the in-millimeter wave dielectric transmission device 100, the signalprocessing board 201 is signal-coupled to the signal processing board101 and the viscoelastic member 107 having a predetermined relativedielectric constant and a predetermined dielectric dissipation factor isprovided between these boards. The viscoelastic member 107 absorbsvibration when external force is applied to the signal processing boards101 and 201, and an electromagnetic wave of a millimeter wave band istransmitted in the viscoelastic member 107 at a high speed.

Struts 10 are provided between the signal processing boards 101 and 201and at four corners of each of the signal processing boards 101 and 201to fix the signal processing boards to each other. As the struts 10, ametal material may be used or a resin material may be used.

As a method for fixing the struts 10 to the signal processing boards 101and 201, the struts 10 may be soldered to positions in which the signalprocessing boards 101 and 201 and the struts 10 are in contact with eachother, a screw may be screwed into a predetermined portion of the strut10, or caulking may be used. Furthermore, by allowing the struts 10themselves to have a spring property (e.g., by using a coil spring andthe like), the vibration of the in-millimeter wave dielectrictransmission device 100 can be absorbed by the struts 10. Consequently,the strut 10 can absorb vibration together with the viscoelastic member107.

In the embodiment, the signal processing board 101 and the signalprocessing board 201 are fixed to each other using the struts 10.However, the struts 10 may be removed and the signal processing boards101 and 201 may be fixed to each other using only the viscoelasticmember 107.

The above-described signal processing board 101 includes a first signalgeneration unit (hereinafter, referred to as a signal generation unit102), a first transmission line (hereinafter, referred to as atransmission line 103), a first antenna unit (hereinafter, referred toas an antenna unit 104), a first insulating layer (hereinafter, referredto as an insulating layer 105), and a first ground wiring pattern(hereinafter, referred to as a ground wiring pattern 106).

The ground wiring pattern 106 is arranged on the entire surface of anupper surface side of the insulating layer 105 constituting the signalprocessing board 101. The ground wiring pattern 106 serves as a groundwiring of the transmission line 103 and a ground wiring of the signalprocessing board 101. The signal generation unit 102, the transmissionline 103 and the antenna unit 104 are arranged at predeterminedpositions of a lower surface side of the insulating layer 105.

Furthermore, the signal processing board 201 includes a second signalgeneration unit (hereinafter, referred to as a signal generation unit202), a second transmission line (hereinafter, referred to as atransmission line 203), a second antenna unit (hereinafter, referred toas an antenna unit 204), a second insulating layer (hereinafter,referred to as an insulating layer 205), and a second ground wiringpattern (hereinafter, referred to as a ground wiring pattern 206).

The ground wiring pattern 206 is arranged on the entire surface of anupper surface side of the insulating layer 205 constituting the signalprocessing board 201. Similar to the ground wiring pattern 106, theground wiring pattern 206 serves as a ground wiring of the transmissionline 203 and a ground wiring of the signal processing board 201. Thesignal generation unit 202, the transmission line 203 and the antennaunit 204 are arranged at predetermined positions of a lower surface sideof the insulating layer 205.

Next, the connection and operation of the in-millimeter wave dielectrictransmission device 100 according to the embodiment will be described.As shown in FIGS. 1 and 2, if an input signal is input to the signalgeneration unit 102, the signal generation unit 102 performs signalprocessing with respect to the received input signal to generate amillimeter wave signal. The transmission line 103 is electricallyconnected to the signal generation unit 102 to transmit the generatedmillimeter wave signal.

In FIGS. 1 and 2, a microstrip line is used as the transmission line103. However, the transmission line 103 may also be formed of a stripline, a coplanar line, a slot line and the like.

The antenna unit 104 is electrically connected to the transmission line103, and has a function to convert the transmitted millimeter wavesignal into an electromagnetic wave and transmit the electromagneticwave. As the antenna unit 104, for example, a patch antenna is used.FIGS. 1 and 2 show a patch antenna.

The viscoelastic member 107 constituting a dielectric transmission pathmakes contact with the antenna unit 104, and the electromagnetic waveconverted by the antenna unit 104 is transmitted to one portion of theviscoelastic member 107. The viscoelastic member 107 has a predeterminedrelative dielectric constant and a predetermined dielectric dissipationfactor, and efficiently transmits an electromagnetic wave of amillimeter wave band. The predetermined relative dielectric constant andthe predetermined dielectric dissipation factor of the viscoelasticmember 107 will be described later with reference to Table 1.

The viscoelastic member 107 makes contact with the antenna unit 204, andthe antenna unit 204 receives the electromagnetic wave transmitted tothe other portion of the viscoelastic member 107 to convert theelectromagnetic wave into a millimeter wave signal. The transmissionline 203 is electrically connected to the antenna unit 204 to transmitthe converted millimeter wave signal. The signal generation unit 202 iselectrically connected to the transmission line 203 to perform signalprocessing with respect to the transmitted millimeter wave signal togenerate an output signal.

In FIGS. 1 and 2, a microstrip line is used as the above-describedtransmission line 203. However, similarly to the transmission line 103,the transmission line 203 may also be formed of a strip line, a coplanarline, a slot line and the like.

Next, details of the signal generation units 102 and 202 will bedescribed. FIG. 3 is a block diagram showing an example of theconfiguration of the in-millimeter wave dielectric transmission device100. As shown in FIG. 3, the signal generation unit 102 includes amodulation circuit 111 and a first frequency conversion circuit(hereinafter, referred to as a frequency conversion circuit 112).

If an input signal is input to the modulation circuit 111, themodulation circuit 111 modulates the received input signal. Thefrequency conversion circuit 112 is connected to the modulation circuit111 to frequency-convert the modulated input signal to generate amillimeter wave signal. The above-described transmission line 103 isconnected to the frequency conversion circuit 112. In order to amplifythe millimeter wave signal, an amplifier 113 may also be provided in thesignal generation unit 102. For example, in FIG. 3, the amplifier 113 isarranged between the frequency conversion circuit 112 and thetransmission line 103.

The signal generation unit 202 includes a second frequency conversioncircuit (hereinafter, referred to as a frequency conversion circuit 212)and a demodulation circuit 211. The frequency conversion circuit 212 isconnected to the above-described transmission line 203 tofrequency-convert a millimeter wave signal transmitted from thetransmission line 203 to output an output signal. The demodulationcircuit 211 is connected to the frequency conversion circuit 212 todemodulate the received output signal. Similarly to the signalgeneration unit 102, in order to amplify the millimeter wave signal, anamplifier 213 may also be provided in the signal generation unit 202.For example, in FIG. 3, the amplifier 213 is arranged between thefrequency conversion circuit 212 and the transmission line 203.

In the embodiment, after the input signal is transmitted from the signalprocessing board 101, the signal processing board 201 receives thetransmitted input signal to generate the output signal. However, thefunction of the signal processing board 101 is provided to the signalprocessing board 201 and the function of the signal processing board 201is provided to the signal processing board 101, so that a millimeterwave signal can be bi-directionally transmitted between the signalprocessing boards.

Next, details of the viscoelastic member 107 according to the presentinvention will be described. The viscoelastic member 107 has apredetermined relative dielectric constant and a predetermineddielectric dissipation factor. For example, as the viscoelastic member107, as shown in Table 1, a dielectric material including an acrylicresin-based, urethane resin-based, epoxy resin-based, silicon-based, orpolyimide-based dielectric material is used.

Furthermore, in order to allow a millimeter wave signal to betransmitted in the viscoelastic member 107 at a high speed, it ispreferable that the viscoelastic member 107 has a relative dielectricconstant of about 3 to about 6 and a dielectric dissipation factor ofabout 0.0001 to about 0.001. Table 1 shows a representative example of adielectric material used for the viscoelastic member 107.

TABLE 1 relative dielectric material name dielectric constantdissipation factor acrylic resin-based 2.5~4.5 0.001~0.05 urethaneresin-based 2.8~4  0.001~0.05 epoxy resin-based 4~6 0.001~0.01silicon-based 3~6 0.0001~0.001 polyimide-based 3~4 0.001~0.01cyanoacrylate-based 3~4 0.001~0.01

Referring to Table 1, the acrylic resin-based dielectric material has arelative dielectric constant of 2.5 to 4.5 and a dielectric dissipationfactor of 0.001 to 0.05. The urethane resin-based dielectric materialhas a relative dielectric constant of 2.8 to 4 and a dielectricdissipation factor of 0.001 to 0.05. The epoxy resin-based dielectricmaterial has a relative dielectric constant of 4 to 6 and a dielectricdissipation factor of 0.001 to 0.01. The silicon-based dielectricmaterial has a relative dielectric constant of 3 to 6 and a dielectricdissipation factor of 0.0001 to 0.001. The polyimide-based dielectricmaterial has a relative dielectric constant of 3 to 4 and a dielectricdissipation factor of 0.001 to 0.01.

The viscoelastic member 107 is provided between the signal processingboard 101 and the signal processing board 201, thereby absorbingvibration when external force is applied to the signal processing boards101 and 201. Furthermore, the viscoelastic member 107 is interposedbetween the signal processing board 101 and the signal processing board201 without using connectors or cables, and a millimeter wave signal canbe transmitted in a vibration environment at a high speed.

Next, a manufacturing method of the in-millimeter wave dielectrictransmission device 100 according to the present invention will bedescribed. FIG. 4 is an exploded perspective view showing an assemblyexample 1 of the in-millimeter wave dielectric transmission device 100.As shown in FIG. 4, the ground wiring pattern 106 is formed on theentire surface of the upper surface side of the insulating layer 105,and the transmission line 103 and the antenna unit 104 are formed at thelower surface side of the insulating layer 105.

The antenna unit 104 has a function of converting a millimeter wavesignal into an electromagnetic wave and transmitting the electromagneticwave to one portion of the viscoelastic member 107 which will bedescribed later. Furthermore, as the insulating layer 105, a resinmaterial such as epoxy resin or acrylic resin is used. The transmissionline 103, the antenna unit 104 and a circuit pattern (not shown) areformed by arranging a metal material such as copper on both surfaces,that is, the upper surface and the lower surface of the insulating layer105, and etching the metal material.

In the assembly example, a patch antenna is used as the antenna unit104. Since the patch antenna can be thinly manufactured similarly to thetransmission line 103 and the circuit pattern, cohesiveness between theantenna unit 104 and the viscoelastic member 107 can be increased,resulting in the achievement of efficient electromagnetic coupling.Furthermore, since the patch antenna has a simple and two-dimensionalphysical shape, it can be manufactured at a low cost.

The signal generation unit 102 for generating a millimeter wave signalby performing signal processing with respect to an input signal isarranged at the lower surface side of the insulating layer 105 in theform of one integrated circuit in which the modulation circuit 111, thefrequency conversion circuit 112 and the amplifier 113 shown in FIG. 3are integrated.

In this way, the signal processing board 101 is manufactured.Furthermore, although detailed description will be omitted, the signalprocessing board 201 can be manufactured in the same manner as that ofthe signal processing board 101 by replacing the signal generation unit102, the transmission line 103, the antenna unit 104, the ground wiringpattern 106, the modulation circuit 111, the frequency conversioncircuit 112 and the amplifier 113 with the signal generation unit 202,the transmission line 203, the antenna unit 204, the ground wiringpattern 206, the demodulation circuit 211, the frequency conversioncircuit 212 and the amplifier 213, respectively.

FIG. 5 is an exploded perspective view showing an assembly example 2 ofthe in-millimeter wave dielectric transmission device 100. As shown inFIG. 5, in the in-millimeter wave dielectric transmission device 100,the viscoelastic member 107 having a predetermined relative dielectricconstant and a predetermined dielectric dissipation factor andconstituting a dielectric transmission path is allowed to make contactwith the upper surface side (the signal generation unit 202, thetransmission line 203 and the antenna unit 204) of the signal processingboard 201 manufactured as described above. At this time, since theviscoelastic member 107 has a predetermined viscosity, the viscoelasticmember 107 makes contact with the signal processing board 201, so thatan air gap can be prevented from being formed therebetween due to inflowof air and the like.

Next, holes into which screws (not shown) are to be inserted areperforated at four corners of each of the signal processing board 101and the signal processing board 201. The struts 10 made of a metalmaterial, resin and the like are vertically installed in the holesformed in the four corners of the signal processing board 201. Screwsare inserted into the four corners formed with the holes from the lowersurface side of the signal processing board 201 and screwed into thestruts 10, so that the struts 10 are fixed to the signal processingboard 201.

The signal processing board 101 is allowed to make contact with thesurface of the viscoelastic member 107, which is opposite to the contactsurface between the signal processing board 201 and the viscoelasticmember 107, by allowing the surface of the signal processing board 101including the signal generation unit 102, the transmission line 103 andthe antenna unit 104 to be directed downward. Then, screws are insertedinto holes perforated at the four corners of the signal processing board101 from the upper surface side of the signal processing board 101 andscrewed into the struts 10, so that the struts 10 are fixed to thesignal processing board 101.

For the fixing of the struts 10, a screw coupling method has beendescribed. However, as described above, the struts 10 may be soldered tothe signal processing boards 101 and 201, or caulking may be used.

According to the manufacturing method as described above, theviscoelastic member 107 having a predetermined relative dielectricconstant and a predetermined dielectric dissipation factor is interposedbetween the signal processing boards, thereby manufacturing thein-millimeter wave dielectric transmission device 100 capable oftransmitting an electromagnetic wave.

Next, the in-millimeter wave dielectric transmission method according tothe present invention will be described. The transmission method of thein-millimeter wave dielectric transmission device 100 manufactured bythe manufacturing method as described above is based on the assumptionthat the signal processing board 101 generates a millimeter wave signalfrom an input signal and transmits the millimeter wave signal to thesignal processing board 201, and the signal processing board 201generates an output signal.

As shown in FIG. 3, an input signal is input to the modulation circuit111 constituting the signal generation unit 102 and modulated by themodulation circuit 111. The modulated input signal isfrequency-converted into a millimeter wave signal by the frequencyconversion circuit 112. The input signal frequency-converted into themillimeter wave signal is amplified by the amplifier 113 and thentransmitted through the transmission line 103.

The transmitted input signal is sent to the antenna unit 104. The inputsignal sent to the antenna unit 104 is converted into an electromagneticwave by the antenna unit 104. The converted electromagnetic wave istransmitted to one portion of the viscoelastic member 107 having apredetermined relative dielectric constant and a predetermineddielectric dissipation factor and constituting a dielectric transmissionpath, and is propagated through the viscoelastic member 107.

Then, the electromagnetic wave transmitted to the other portion of theviscoelastic member 107 by propagating through the viscoelastic member107 is received in the antenna unit 204 and converted into a millimeterwave signal. The converted millimeter wave signal is transmitted to thetransmission line 203 and then amplified by the amplifier 213constituting the signal generation unit 202. The amplified millimeterwave signal is frequency-converted by the frequency conversion circuit212, resulting in the generation of an output signal. The generatedoutput signal is demodulated by the demodulation circuit 211 and thenoutput.

According to the transmission method as described above, theviscoelastic member 107 having a predetermined relative dielectricconstant and a predetermined dielectric dissipation factor is interposedbetween the signal processing board 101 and the signal processing board201 without using connectors or cables, and a millimeter wave signal canbe transmitted in a vibration environment at a high speed.

Next, a simulation result of the millimeter wave signal transmission ofthe in-millimeter wave dielectric transmission device 100 according tothe present invention will be described. FIG. 6 is a graph showing anexample of characteristics of the in-millimeter wave dielectrictransmission device 100 according to the simulation. The simulationresult shown in FIG. 6 is obtained based on parameter values as shown inTable 2 using the in-millimeter wave dielectric transmission device 100having the configuration shown in FIG. 1.

Furthermore, as shown in FIG. 6, in the simulation result, a horizontalaxis denotes the frequency (GHz) of an electromagnetic wave signal and avertical axis denotes the intensity (dB) of an S-parameter. TheS-parameter indicates transmission and reflection of an electromagneticwave, and as shown in FIG. 6, a solid line indicates a transmissionproperty 301 and a broken line indicates a reflection property 302.

TABLE 2 parameter value unit one side of patch antenna 1 mm thickness ofsignal processing board 0.1 mm line width of microstrip line 0.2 mmdistance between signal processing boards 10 mm relative dielectricconstant of signal processing board 3.5 none dielectric dissipationfactor of signal processing board 0.005 none relative dielectricconstant of viscoelastic member 5.4 none dielectric dissipation factorof viscoelastic member 0.0006 none

In the simulation result, a patch antenna is used as the antenna units104 and 204 shown in FIG. 1. One side of the patch antenna has a squareshape of 1 mm and the thickness thereof is 0.1 mm. The transmissionlines 103 and 203 use a microstrip line and the line width thereof is0.2 mm. Furthermore, the viscoelastic member 107 provided between thesignal processing board 101 and the signal processing board 201 has athickness of 10 mm. Herein, the thicknesses of the patch antenna and theviscoelastic member 107 are defined as the size in the verticaldirection of predetermined surfaces of the signal processing boards 101and 201.

The insulating layers 105 and 205 use glass epoxy resin and have arelative dielectric constant of 3.5 and a dielectric dissipation factorof 0.005. Furthermore, the viscoelastic member 107 uses liquid siliconrubber and has a relative dielectric constant of 5.4 and a dielectricdissipation factor of 0.0006.

Referring to FIG. 6, as can be seen from the simulation result, thetransmission property 301 shows the strength of the S-parameter higherthan that of the reflection property 302 in the frequency range of 58GHz to 58.7 GHz of an electromagnetic wave. This represents that datatransmission is possible in the frequency band of 58 GHz to 58.7 GHz ofthe electromagnetic wave.

As described above, in the in-millimeter wave dielectric transmissiondevice 100 according to the embodiment, the viscoelastic member 107having a predetermined relative dielectric constant and a predetermineddielectric dissipation factor is provided between the signal processingboard 101 and the signal processing board 201. With such aconfiguration, the viscoelastic member 107 absorbs vibration whenexternal force is applied to the signal processing boards 101 and 201,so that the vibration of the signal processing board 101 and the signalprocessing board 201 can be reduced.

Furthermore, the viscoelastic member 107 is interposed between thesignal processing board 101 and the signal processing board 201 withoutusing connectors or cables, and a millimeter wave signal can betransmitted in a vibration environment at a high speed. Consequently, itis possible to provide the in-millimeter wave dielectric transmissiondevice 100 capable of performing high speed signal transmission withhigh reliability.

In addition, one or more third signal processing boards (not shown) areprovided at an outer side of the signal processing board 101 and/or atan outer side of the signal processing board 201 through a secondviscoelastic member (not shown) providing a dielectric transmission pathdifferent from that of the viscoelastic member 107 provided between thesignal processing board 101 and the signal processing board 201, so thatthe second viscoelastic member may also constitute the dielectrictransmission path. The second viscoelastic member has a predeterminedrelative dielectric constant and a predetermined dielectric dissipationfactor.

Consequently, it is possible to reduce the vibration of the signalprocessing boards 101 and 201 and the third signal processing board, andto transmit a millimeter wave signal at a high speed through the secondviscoelastic member having a predetermined relative dielectric constantand a predetermined dielectric dissipation factor, which is providedbetween the signal processing boards without using connectors or cables.

[First Embodiment]

FIG. 7 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100A according to afirst embodiment and FIG. 8 is a sectional view of the in-millimeterwave dielectric transmission device 100A shown in FIG. 7. In thein-millimeter wave dielectric transmission device 100A shown in FIGS. 7and 8, a housing 20 is provided at the lower surface side of the signalprocessing board 201 of the above-described in-millimeter wavedielectric transmission device 100 through a viscoelastic member 207.Since the same names and reference numerals are used to designate thesame elements as those of the embodiment, detailed description thereofwill be omitted.

As shown in FIGS. 7 and 8, in the in-millimeter wave dielectrictransmission device 100A, the viscoelastic member 207 makes contact withthe surface of the ground wiring pattern 206 formed on the signalprocessing board 201 of the above-described in-millimeter wavedielectric transmission device 100. Furthermore, the housing 20 makescontact with a surface of the viscoelastic member 207, which is oppositeto the contact surface between the ground wiring pattern 206 and theviscoelastic member 207.

Similar to the above-described viscoelastic member 107, the viscoelasticmember 207 has a predetermined relative dielectric constant and apredetermined dielectric dissipation factor, and for example, uses adielectric material including an acrylic resin-based, urethaneresin-based, epoxy resin-based, silicon-based, or polyimide-baseddielectric material.

As described above, in the in-millimeter wave dielectric transmissiondevice 100A according to the first embodiment, the viscoelastic member207 is provided between the housing 20 and the signal processing board201, so that an anti-vibration property and an anti-collision propertyare further enhanced, as compared with the in-millimeter wave dielectrictransmission device 100.

Consequently, the viscoelastic member 207 is provided between the signalprocessing board 201 and the housing 20, so that it is possible tosuppress vibration when external force is applied to the in-millimeterwave dielectric transmission device 100A provided with the housing 20.

[Second Embodiment]

FIG. 9 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100B according to asecond embodiment and FIG. 10 is a sectional view of the in-millimeterwave dielectric transmission device 100B shown in FIG. 9. In thein-millimeter wave dielectric transmission device 100B shown in FIGS. 9and 10, adhesive 30 is used for adhesion between the signal processingboard 101 and the viscoelastic member 107, between the viscoelasticmember 107 and the signal processing board 201, between the signalprocessing board 201 and the viscoelastic member 207, and between theviscoelastic member 207 and the housing 20, which are included in thein-millimeter wave dielectric transmission device 100A described in thefirst embodiment. Since the same names and reference numerals are usedto designate the same elements as those of the first embodiment,detailed description thereof will be omitted.

As shown in FIGS. 9 and 10, in the in-millimeter wave dielectrictransmission device 100B, the adhesive 30 is coated between theviscoelastic member 107 and the signal processing board 101, between theviscoelastic member 107 and the signal processing board 201, between theviscoelastic member 207 and the signal processing board 201, and betweenthe viscoelastic member 207 and the housing 20.

The adhesive 30 uses a dielectric material including an acrylicresin-based, urethane resin-based, epoxy resin-based, silicon-based,polyimide-based, cyanoacrylate-based dielectric material, etc. Theacrylic resin-based, urethane resin-based, epoxy resin-based,silicon-based, polyimide-based, and cyanoacrylate-based dielectricmaterial and the like have superior adhesiveness and cohesiveness, andhave the predetermined relative dielectric constant and thepredetermined dielectric dissipation factor shown in Table 1. Thus, theadhesive 30 does not disturb an electromagnetic wave of a millimeterwave band which is transmitted through the viscoelastic member 107.

A manufacturing method of the in-millimeter wave dielectric transmissiondevice 100B according to the second embodiment further includes a stepof coating the adhesive 30 onto predetermined surfaces of theviscoelastic members 107 and 207 of the in-millimeter wave dielectrictransmission device 100 and opposite surfaces thereof, which aredescribed in the embodiment. Since the same names and reference numeralsare used to designate the same elements as those of the embodiment,detailed description thereof will be omitted.

The adhesive 30 is coated onto the predetermined surfaces of theviscoelastic members 107 and 207 and the opposite surfaces thereof at athickness of 1 mm or less. For the coating method, for example, adispenser, a printing machine, an inkjet and the like are used. Theviscoelastic members 107 and 207 coated with the adhesive 30 areprovided between the signal processing board 101 and the signalprocessing board 201 and between the signal processing board 201 and thehousing 20, thereby manufacturing the in-millimeter wave dielectrictransmission device 100B shown in FIGS. 9 and 10 according to the secondembodiment.

As described above, in the in-millimeter wave dielectric transmissiondevice 100B according to the second embodiment, by coating the adhesive30 onto the viscoelastic members 107 and 207, cohesiveness between thesignal processing boards 101 and 201 and the viscoelastic members 107and 207 and between the housing 20 and the viscoelastic member 207 isincreased, so that the viscoelastic members 107 and 207 can furtherabsorb vibration, resulting in a further reduction in the vibration ofthe signal processing boards 101 and 201 and the housing 20. Inaddition, cohesiveness between the signal processing boards 101 and 201and the viscoelastic member 107 is increased and the absorption,reflection and external leakage of an electromagnetic wave are reduced,so that a millimeter wave signal can be efficiently transmitted at ahigh speed.

[Third Embodiment]

FIG. 11 is a perspective view showing an example of the configuration ofan in-millimeter wave dielectric transmission device 100C according to athird embodiment and FIG. 12 is a sectional view of the in-millimeterwave dielectric transmission device 100C shown in FIG. 11. In thein-millimeter wave dielectric transmission device 100C shown in FIGS. 11and 12, the antenna unit 104 and the antenna unit 204, which areincluded in the in-millimeter wave dielectric transmission device 100Bdescribed in the second embodiment, are replaced with a first slot(hereinafter, referred to as a slot 110) and a second slot (hereinafter,referred to as a slot 210), respectively. Since the same names andreference numerals are used to designate the same elements as those ofthe second embodiment, detailed description thereof will be omitted.

As shown in FIGS. 11 and 12, the in-millimeter wave dielectrictransmission device 100C includes a signal processing board 401, asignal processing board 501 and the viscoelastic member 107.

A first signal processing board (hereinafter, referred to as the signalprocessing board 401) includes the signal generation unit 102, thetransmission line 103, the insulating layer 105, the ground wiringpattern 106 and the slot 110. The signal generation unit 102 and thetransmission line 103 are arranged at the upper surface side of theinsulating layer 105. The ground wiring pattern 106 is arranged on theentire surface of the lower surface side of the insulating layer 105.

The slot 110 is provided at a predetermined position of the groundwiring pattern 106 which is an opposite surface side of the transmissionline 103. For example, in relation to the size of the slot 110, the slot110 has a length of about 0.1 mm to about 0.2 mm in the direction of thetransmission line 103, and a length corresponding to ½ of the wavelengthof a millimeter wave signal used, in the direction perpendicular to thedirection of the transmission line 103.

The slot 110 serves as a slot antenna. In the slot antenna, a currentflowing through the surface of the transmission line 103 is interruptedby the slot 110 and an electric field is generated at the interruptionposition. In this way, the slot antenna converts a millimeter wavesignal into an electromagnetic wave.

Similarly to the manufacturing method of the patch antenna, the slotantenna is manufactured simultaneously when manufacturing thetransmission lines 103 and 203 and circuit patterns (not shown) of thesignal processing board 401 and the signal processing board 501 (whichwill be described later) through an etching process.

Since the slot antenna is used in the in-millimeter wave dielectrictransmission device 100C and the directivity of the slot antenna islower than that of the patch antenna, the external leakage of anelectromagnetic wave propagating through the viscoelastic member 107 canbe reduced and the influence of external noise can also be reduced.

A second signal processing board (hereinafter, referred to as the signalprocessing board 501) includes the signal generation unit 202, thetransmission line 203, the insulating layer 205, the ground wiringpattern 206 and the slot 210.

The signal generation unit 202 and the transmission line 203 arearranged at the upper surface side of the insulating layer 205. Theground wiring pattern 206 is arranged on the entire surface of the lowersurface side of the insulating layer 205. Furthermore, the slot 210 isprovided at a predetermined position of the ground wiring pattern 206which is an opposite surface side of the transmission line 203. The slot210 also serves as a slot antenna, similarly to the slot 110. The slot210 has the same size as the slot 110.

The viscoelastic member 107 having a predetermined relative dielectricconstant and a predetermined dielectric dissipation factor is providedbetween the signal processing board 401 and the signal processing board501 which are configured as described above. At this time, the adhesive30 is coated onto the predetermined surface of the viscoelastic member107 and the opposite surface thereof.

Since the viscoelastic member 107 and the adhesive 30 have apredetermined viscosity, they can be provided between the signalprocessing boards such that an air gap is not formed due to inflow ofair and the like, while the adhesive does not penetrate into the slots110 and 210.

As described above, in the in-millimeter wave dielectric transmissiondevice 100C according to the third embodiment, the slots 110 and 210serve as a slot antenna, and the viscoelastic member 107 is interposedbetween the signal processing board 401 and the signal processing board501 without using connectors or cables, and a millimeter wave signal canbe transmitted in a vibration environment at a high speed. Consequently,it is possible to provide the in-millimeter wave dielectric transmissiondevice 100C capable of transmitting a millimeter wave signal at a highspeed with high reliability using a slot antenna.

The present invention can be extremely effectively applied to anin-millimeter wave dielectric transmission device used for ananti-collision radar system of a vehicle and the like.

Reference Signs List

20 housing, 30 adhesive, 100, 100A, 100B, 100C in-millimeter wavedielectric transmission device, 101, 401 first signal processing board,102 first signal generation unit, 103 first transmission line, 104 firstantenna unit, 105 first insulating layer, 106 first ground wiringpattern, 107, 207 viscoelastic member, 110 first slot, 111 modulationunit, 112 first frequency conversion circuit, 113, 213 amplifier, 201,501 second signal processing board, 202 second signal generation unit,203 second transmission line, 204 second antenna unit, 205 secondinsulating layer, 206 second ground wiring pattern, 210 second slot, 211demodulation circuit, 212 second frequency conversion circuit

The invention claimed is:
 1. A transmission device comprising: a firstsignal processing board for processing a millimeter wave signal; asecond signal processing board signal-coupled to the first signalprocessing board to receive the millimeter wave signal and performsignal processing with respect to the millimeter wave signal; and aviscoelastic member provided between the first signal processing boardand the second signal processing board and having a predeterminedrelative dielectric constant and a predetermined dielectric dissipationfactor, wherein, the viscoelastic member constitutes a dielectrictransmission path via which the millimeter wave signal is transmittedbetween the first signal processing board and the second signalprocessing board.
 2. The transmission device according to claim 1,wherein: (a) the first signal processing board includes (i) a firstsignal generation unit for generating the millimeter wave signal byperforming signal processing with respect to an input signal, and (ii) afirst antenna unit for converting the millimeter wave signal generatedby the first signal generation unit into an electromagnetic wave andtransmitting the electromagnetic wave to one portion of the viscoelasticmember constituting the dielectric transmission path, and (b) the secondsignal processing board includes (i) a second antenna unit for receivingthe electromagnetic wave transmitted to another portion of theviscoelastic member constituting the dielectric transmission path andconverting the electromagnetic wave into the millimeter wave signal, and(ii) a second signal generation unit for generating an output signal byperforming signal processing with respect to the millimeter wave signalconverted by the second antenna unit.
 3. The transmission deviceaccording to claim 2, wherein: the first signal processing boardincludes a first transmission line which is electrically connectedbetween the first signal generation unit and the first antenna unit totransmit the millimeter wave signal, and the second signal processingboard includes a second transmission line which is electricallyconnected between the second signal generation unit and the secondantenna unit to transmit the millimeter wave signal.
 4. The transmissiondevice according to claim 3, wherein the first transmission line and thesecond transmission line include at least one of a strip line, amicrostrip line, a coplanar line and a slot line.
 5. The transmissiondevice according to claim 3, wherein the first antenna unit and thesecond antenna unit include at least a patch antenna or a slot antenna.6. The transmission device according to claim 3, wherein: (a) the firstsignal generation unit includes (i) a modulation circuit for modulatingthe input signal, and (ii) a first frequency conversion circuit forgenerating the millimeter wave signal by frequency-converting the inputsignal modulated by the modulation circuit, and (b) the second signalgeneration unit includes (i) a second frequency conversion circuit foroutputting the output signal by frequency-converting the millimeter wavesignal; and (ii) a demodulation circuit for demodulating the outputsignal which is output from the second frequency conversion circuit. 7.The transmission device according to claim 6, wherein the first signalgeneration unit and the second signal generation unit respectivelyinclude amplifiers for amplifying the millimeter wave signal.
 8. Thetransmission device according to claim 2, wherein the viscoelasticmember includes a dielectric material, the dielectric material includingat least an acrylic resin-based, urethane resin-based, epoxyresin-based, silicon-based, or polyimide-based dielectric material. 9.The transmission device according to claim 2, wherein anotherviscoelastic member is provided between the first signal processingboard or the second signal processing board and a housing.
 10. Thetransmission device according to claim 9, wherein an adhesive is usedfor adhesion between the first and second signal processing boards andthe viscoelastic member, and between the housing and the otherviscoelastic member.
 11. The transmission device according to claim 10,wherein the adhesive includes a dielectric material, the dielectricmaterial including at least an acrylic resin-based, urethaneresin-based, epoxy resin-based, cyanoacrylate-based, silicon-based, orpolyimide-based dielectric material.
 12. The transmission deviceaccording to claim 1, wherein the viscoelastic member absorbs vibrationwhen an external force is applied to the first signal processing boardor the second signal processing board.
 13. A method for manufacturing atransmission device, comprising: forming a first signal processing boardfor processing a millimeter wave signal; forming a second signalprocessing board for receiving the millimeter wave signal from the firstsignal processing board and performing signal processing with respect tothe millimeter wave signal; and providing a viscoelastic member having apredetermined relative dielectric constant and a predetermineddielectric dissipation factor between the first signal processing boardand the second signal processing board, wherein, the viscoelastic memberconstitutes a dielectric transmission path via which the millimeter wavesignal is transmitted between the first signal processing board and thesecond signal processing board.
 14. The method according to claim 13,wherein: when forming the first signal processing board, a first signalgeneration unit for generating the millimeter wave signal by performingsignal processing with respect to an input signal, and a first antennaunit for converting the millimeter wave signal generated by the firstsignal generation unit into an electromagnetic wave and transmitting theelectromagnetic wave to one portion of the viscoelastic memberconstituting the dielectric transmission path are disposed on apredetermined surface of the first signal processing board, and whenforming the second signal processing board, a second antenna unit forreceiving the electromagnetic wave transmitted to another portion of theviscoelastic member constituting the dielectric transmission path andconverting the electromagnetic wave into the millimeter wave signal, anda second signal generation unit for generating an output signal byperforming signal processing with respect to the millimeter wave signalconverted by the second antenna unit are disposed on a predeterminedsurface of the second signal processing board.
 15. The method accordingto claim 14, wherein an adhesive is coated onto respective surfaces ofthe viscoelastic member, and the viscoelastic member coated with theadhesive is provided between the first signal processing board and thesecond signal processing board.
 16. The method according to claim 13,wherein the Viscoelastic member absorbs vibration when an external forceis applied to the first signal processing board or the second signalprocessing board.
 17. A transmission method for an in-millimeter wavedielectric transmission device having a first signal processing boardand a second signal processing board, the method comprising: generatingat the first signal processing board a millimeter wave signal byperforming signal processing with respect to an input signal; convertingat the first signal processing board the millimeter wave signal into anelectromagnetic wave; transmitting the millimeter wave signal convertedinto the electromagnetic wave through a viscoelastic member providedbetween the first signal processing board and the second signalprocessing board, the viscoelastic member having a predeterminedrelative dielectric constant and a predetermined dielectric dissipationfactor and constituting a dielectric transmission path via which themillimeter wave signal is transmitted between the first signalprocessing board and the second signal processing board; receiving theelectromagnetic wave transmitted through the viscoelastic member at thesecond signal processing board; converting at the second signalprocessing board the electromagnetic wave into the millimeter wavesignal; and generating at the second signal processing board an outputsignal by performing signal processing with respect to the millimeterwave signal.
 18. The method according to claim 17, wherein theviscoelastic member absorbs vibration when an external force is appliedto the first signal processing board or the second signal processingboard.